1. Field of the Invention
The present invention relates generally to an optical lens assembly, and more particularly to a dustproof lens assembly.
2. Description of the Related Art
FIG. 1 shows an image catch unit 1 of an electronic product, such as digital camera, digit personal assistant (PDA), and mobile phone, includes an optical lens assembly 2 and an image sensor 3. The image sensor 3 is electrically connected to a flexible printed circuit board (FPCB) 4, and the optical lens assembly 2 is mounted on the image sensor 3. The optical lens assembly 2 includes a holder 5, on a bottom of which the image sensor 3 is provided, a barrel 6 mounted on the holder 5 and lens 7 mounted in the barrel 6. Light is emitted to the image sensor 3 through the lens 7 and the holder 5 to generate an image signal. The FPCB 4 receives the image signal and transmits it to a circuit board of the electronic product.
The barrel 6 and the holder 5 have a threaded section 8 respectively so that the barrel 6 is screwed into the holder 5. We find that dust always is received between the threaded sections 8 of the barrel 6 and the holder 5 and will drop onto the image sensor 3 when the image catch unit 1 is moved or vibrated. The dust on the image sensor 3 will greatly affect a performance of the image sensor 3.
An improved lens assembly was provided to avoid the dust problem, which provides a film around the image sensor to block the dust. In practice, the film blocks the dust under the image sensor only. The dust between the threaded sections of the barrel and the holder still drops onto the image sensor directly rather than onto the film while the image catch unit is leaning. As a result, this lens assembly still has dust on the image sensor.